#!/usr/bin/python
# -*- coding: utf-8 -*-

def Converter(str, output):
    #output=''
    if (len(str)) > 20:
        output='ERROR!'
    if (len(str)) <= 20:
        for i in range(len(str)):
            if str[i] not in '0123456789abcdefghijklmnopqrstuvwxyz':
                output = 'ERROR!'
                break
            if i%2==0:
                output+=str[i]
    print (output)
    #return output

if __name__=='__main__':
    str = raw_input()
    output=''
    output=Converter(str,output)
    #print (output)


